Reducing Our Risk

New Orleans Redevelopment Authority (NORA)

Entry Overview

New Orleans has experienced 76 recorded flood events since 1950. Approximately 95,000 structures in New Orleans are located in the floodplain and over $7 billion in flood insurance damage claims have been filed in the city since the advent of the National Flood Insurance Program. New Orleans is physically vulnerable to flooding due to its geographic location and topography, but the impacts of flooding in the city are often magnified by the social vulnerability of area residents. More than 27% of New Orleans citizens live below the poverty line and lack the resources to quickly and effectively recover from natural disasters. The New Orleans Redevelopment Authority (NORA) currently owns over 2,300 vacant properties throughout the city. In addition to engaging in traditional redevelopment activities, the agency is committed to utilizing vacant properties to manage stormwater and mitigate flooding. Consequently, NORA has constructed five raingardens and made approximately 1,000 vacant lots available for greenspace projects since 2009. The agency is also currently designing a large-scale stormwater management project that is intended to bring proven stormwater management concepts to scale.

General Info
Email :
Organization Address: 
1409 Oretha Castle Haley Blvd.
New Orleans, Louisiana 70113
United States
Population Impacted: 
Identify the likelihood and frequency of this hazard : 
A theoretical 10-year storm event (10% annual chance of occurrence) in New Orleans produces an average rainfall of 8.5 inches and a peak one-hour rainfall of 3.43 inches. However, the National Climatic Data Center (NCDC) has recorded 76 actual flood events in New Orleans from 1950 through 2014. NCDC-reported events indicate that there is an 84% probability that at least one flood event will occur in New Orleans each year.
Explain how vulnerable the community is to this hazard: 
In terms of physical vulnerability, 69% of all structures in New Orleans (over 95,000 structures) are located in the floodplain. Approximately 5,000 structures are classified by the National Flood Insurance Program (NFIP) as Repetitive Loss (RL). RL structures alone have accounted for over 17,000 NFIP claims and $550 million in damage citywide. In terms of social vulnerability, 27.3% of the population in New Orleans lives below the poverty level.
List the potential affects of this hazard: 
NFIP policyholders in New Orleans file an average of over $240 million in property damage claims each year. A total of 120,657 NFIP claims ($7.1 billion in property damage) have been filed in Orleans Parish since the advent of the NFIP. However, these figures do not account for the loss of life; injury; interruption of commerce; displacement; and general inconveniences that also occur as a result of flood events.
Identify how sensitive the community is to these affects: 
Given the geographic location and history of flooding in the city, New Orleanians are highly sensitive to flood events and their associated effects. Traditional structural flood mitigation measures such as levees, subsurface drainage, and pumping stations are highly visible elements of the urban landscape in New Orleans, although such measures have proven to be expensive to maintain and prone to failure.
Preparedness Goal: 
NORA is actively implementing projects and programs which utilize vacant space for the purpose of stormwater management and flood mitigation.
Implementing Actions: 

NORA’s goal is to utilize vacant space for the purpose of stormwater management and flood mitigation. The Urban Water Plan (UWP) is focused on the utilization of vacant public space and other resources for the purposes of stormwater management, creating economic development opportunities, and improving quality of life. NORA has played a leading role in promoting the UWP by leveraging its inventory of vacant property to implement projects and programs that meet plan objectives. The agency has completed a number of pilot raingarden projects and is actively scoping new projects. Additionally, NORA has implemented two UWP-inspired greenspace programs. NORA has constructed five (5) raingardens on vacant lots throughout the city. Each project has tested various stormwater management interventions for the purpose of scaling larger, more impactful projects in the future. The interventions tested thus far will be brought to scale in the agency’s proposed $15 million Pontilly Stormwater Mitigation Project. The Pontilly project is being designed as a vast network of stormwater management interventions that span two adjacent flood prone neighborhoods, including features such as raingardens, bioswales, open drainage canal improvements, permeable pavement, and curb bulb-outs. In addition to actively managing stormwater on vacant public space by constructing raingardens, NORA has also been engaged in passively managing stormwater by encouraging the maintenance of vacant property as greenspace. NORA has accomplished this by offering discounts on the sale of vacant property in exchange for green improvements made by the buyer. This program (Growing Home) has thus far yielded over $7.5 million of private investment in greenspace on 927 vacant properties (approximately 135 acres). NORA also administers a separate program (Growing Green) whereby vacant properties are leased or sold for urban agriculture and general greening projects. To date, approximately 70 vacant properties have been leased or sold to private entities for projects such as hydroponic farms, community gardens, and dog parks.

Describe Your Solution: 

There are currently two primary NORA raingarden project typologies. The first typology includes a basic design (light grading, landscaping, and the installation of various pervious surfaces) that is intended to capture stormwater on-site. The second, more intense typology includes the basic features described above as well as a runnel and meter box system which is designed to capture stormwater on-site and stormwater flow from adjacent streets. Each raingarden project typology reduces the risk of flooding by controlling the rate at which stormwater enters the existing drainage system (grey infrastructure), thereby decreasing the likelihood of the system becoming overwhelmed during intense rain events. NORA views the installation of raingardens as an effective means of actively managing stormwater in flood prone neighborhoods. NORA also recognizes the value of passively managing stormwater in flood prone neighborhoods by encouraging the maintenance of vacant property as greenspace. The agency’s Growing Home and Growing Green programs accomplish this by granting private entities access to publicly-owned vacant space and incentivizing investment in greenspace projects. Approximately 1,000 vacant properties are now being maintained as greenspace as a result of the two aforementioned programs. The combined actions of managing stormwater via raingarden installation and passively managing stormwater by encouraging the maintenance of vacant property as greenspace reduce the risk of flooding by providing new spaces for stormwater to be temporarily stored. The temporary storage of stormwater decreases the likelihood of the existing drainage infrastructure being overwhelmed during intense storm events. Furthermore, temporarily storing stormwater (as opposed to rapidly draining and pumping the water out) also helps maintain the water table, which reduces subsidence and preserves the condition and capacity of grey drainage infrastructure.


Raingardens are aesthetically pleasing amenities that have improved the marketability of other adjacent vacant properties. Greenspace projects facilitated by NORA have resulted in at least $7.5 million in direct investment and have also had a positive effect on the marketability of other adjacent vacant properties. Studies conducted around the world have shown that greenspace can positively impact adjacent property values by as much as 5%. Overall, greenspace interventions in post-Katrina New Orleans have the potential to be major catalysts for redevelopment in a city where over 2,300 publicly-owned vacant properties currently exist.


In addition to their value as flood mitigation tools, raingardens and greenspace provide a natural filtration system for stormwater. As these interventions capture and temporarily store stormwater, pollutants are filtered out of the water prior to entering the existing drainage infrastructure and being pumped into nearby Lake Pontchartrain. This has the effect of mitigating the negative impacts of urban stormwater runoff and improving overall water quality in one of nation’s largest lakes.


Throughout the process of installing raingardens and implementing greenspace programs, NORA has forged partnerships with a diverse group of neighbors, neighborhood associations, non-profit organizations, private entities, and educational institutions. The agency has utilized its network of partners not only to beautify neighborhoods and build a sense of community around raingarden and greenspace projects, but also to leverage resources for other community development initiatives such as financial literacy and the provision of fresh produce in underserved neighborhoods.

What were the negative or unintended impacts (if any) associated with implementing this solution? : 

In instances where NORA has engaged in raingarden or greenspace projects that do not involve the sale or lease of vacant property, the initial costs associated with design and installation have been significant. Additionally, the long-term maintenance costs associated with such projects far exceed what NORA typically expends on routine annual maintenance. In response to the above challenges, NORA recently doubled its community outreach efforts in an attempt to forge partnerships with neighborhood associations that have demonstrated the willingness and capacity to share the financial burden associated with the design, installation, and maintenance of raingarden or greenspace projects. These efforts have been met with initial success, as NORA recently engaged two neighborhood associations in sharing the costs associated with two large-scale greenspace projects that will impact approximately five acres of vacant space. These two projects have now become pilots for a new typology that NORA refers to as Community-Based Design and Maintenance.

Return on Investment: How much did it cost to implement these activities? How do your results above compare to this investment?: 

NORA has spent over $150,000 on raingarden projects and is poised to spend several hundred thousand more. Although the full range of benefits is difficult to quantify at this time, the agency believes the potential long-term economic, environmental, and social benefits make replicating these projects viable. Lessons learned from the initial round of raingarden projects are being taken into consideration as future projects are scoped, and NORA continues to work at minimizing costs while maximizing benefits, as the agency has demonstrated in its two forthcoming Community-Based Design and Maintenance projects. Greenspace programs administered by NORA involve the sale or lease of vacant property to private entities, thus relieving the agency of the financial burden associated with property maintenance. The agency saves no less than $450 per year on maintenance costs for each vacant property that is made available for sale or lease. Although NORA provides for discounts on the sale price of vacant property through its Growing Home program, the dollar amount of the discount must be matched by the dollar value of green improvements made by the buyer. Consequently, the economic, environmental, and social benefits realized as a result of NORA’s greenspace programs make the programs viable going forward.

What are the main factors needed to successfully replicate this solution elsewhere?: 

Replicating raingarden projects requires the identification of neighborhoods that are: a.) flood prone, as evidenced by NFIP claims and/or other data regarding persistent nuisance flooding; and b.) in close proximity to vacant lots and/or other public spaces that may be utilized to store stormwater. Community education, outreach and participation are also critical components of replicating raingarden projects. In terms of replicating the types of greenspace projects that have been implemented as a result of NORA’s greenspace programs, promoting awareness and making the appropriate vacant properties available for sale or lease are both essential. Additionally, providing technical assistance to program participants is critical. In an effort to maximize the potential of proposed greenspace projects, NORA recently enlisted the services of Parkway Partners, a local non-profit with expertise in landscaping and horticulture. Parkway Partners provides technical assistance to program participants at no cost, and is currently working closely with approximately ten program participants to complete a number of greenspace projects.

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Reducing Our Risk

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